You posted in Emacs Lisp forum, but as far as I know lisp-in-a-box is a Common Lisp implementation bundled with Emacs? Which Lisp are you using (Emacs Lisp and Common Lisp are quite different). In any case, write your definitions in a file in the first place and load the files (or single forms using appropriate Emacs commands), rather than writing into the REPL or scratch buffer.

Well, it looks like you are struggling with Emacs. Try Emacs' tutorial. When you open Emacs, there should be a link to it, or you can start it hitting C-h t (hold the Ctrl button and press H, then release and press T) or from the Help menu.

To open a file, use C-x C-f (hold Ctrl, press x, hold Ctrl and press f). Always open a file to create a new file. To save, C-x C-s. You can also save / open from the File menu.

Emacs is very powerful once you learn it, but, if you want a more standard editor, you can try Cusp, a plugin for Eclipse (take a look at this tutorial).